.NET的简单事件总线

Question

我想创建一个非常简单的事件总线,它允许任何客户端订阅特定类型的事件,当任何发布者使用EventBus.PushEvent()方法在总线上推送事件时,只有订阅该特定事件类型的客户端才能获得该事件.

我正在使用C#和.NET 2.0.

Answer 1

Tiny Messenger是一个不错的选择,我已经在现场项目中使用它已有2.5年了.来自Wiki的一些代码示例(链接如下):

出版

messageHub.Publish(new MyMessage());

订阅

messageHub.Subscribe<MyMessage>((m) => { MessageBox.Show("Message Received!"); });
messageHub.Subscribe<MyMessageAgain>((m) => { MessageBox.Show("Message Received!"); }, (m) => m.Content == "Testing");

代码在GitHub上:https://github.com/grumpydev/TinyMessenger

Wiki似乎仍然在BitBucket上:https://bitbucket.org/grumpydev/tinyioc/wiki/TinyMessenger

它还有一个Nuget包

Install-Package TinyMessenger

Answer 2

另一个,受到EventBus for android的启发,但更简单:

public class EventBus
{
    public static EventBus Instance { get { return instance ?? (instance = new EventBus()); } }

    public void Register(object listener)
    {
        if (!listeners.Any(l => l.Listener == listener))
            listeners.Add(new EventListenerWrapper(listener));
    }

    public void Unregister(object listener)
    {
        listeners.RemoveAll(l => l.Listener == listener);
    }

    public void PostEvent(object e)
    {
        listeners.Where(l => l.EventType == e.GetType()).ToList().ForEach(l => l.PostEvent(e));
    }

    private static EventBus instance;

    private EventBus() { }

    private List<EventListenerWrapper> listeners = new List<EventListenerWrapper>();

    private class EventListenerWrapper
    {
        public object Listener { get; private set; }
        public Type EventType { get; private set; }

        private MethodBase method;

        public EventListenerWrapper(object listener)
        {
            Listener = listener;

            Type type = listener.GetType();

            method = type.GetMethod("OnEvent");
            if (method == null)
                throw new ArgumentException("Class " + type.Name + " does not containt method OnEvent");

            ParameterInfo[] parameters = method.GetParameters();
            if (parameters.Length != 1)
                throw new ArgumentException("Method OnEvent of class " + type.Name + " have invalid number of parameters (should be one)");

            EventType = parameters[0].ParameterType;
        }

        public void PostEvent(object e)
        {
            method.Invoke(Listener, new[] { e });
        }
    }      
}

使用案例:

public class OnProgressChangedEvent
{

    public int Progress { get; private set; }

    public OnProgressChangedEvent(int progress)
    {
        Progress = progress;
    }
}

public class SomeForm : Form
{
    // ...

    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        EventBus.Instance.Register(this);
    }

    public void OnEvent(OnProgressChangedEvent e)
    {
        progressBar.Value = e.Progress;
    }

    protected override void OnClosed(EventArgs e)
    {
        base.OnClosed(e);
        EventBus.Instance.Unregister(this);
    }
}

public class SomeWorkerSomewhere
{
    void OnDoWork()
    {
        // ...

        EventBus.Instance.PostEvent(new OnProgressChangedEvent(progress));

        // ...
    }
}

Answer 3

我找到了通用消息总线。这是一堂简单的课。